A user may communicate with a network based application such as a service application via a communication system. A communication system is a facility which enables communication between two or more entities such as user terminal devices or other communication devices, network entities and other nodes. The communication may comprise, for example, communication of voice, electronic mail (email), text messages, data, multimedia and so on. The communication can be related to use of various services provided by service applications. The applications are typically provided by means of application servers connected to a data network.
A user accesses a communication system via an access interface. An access interface is typically provided by an access system, for example an access network. An access system typically provides the access interface in accordance with a given standard or with a given set of specifications which set out what the various elements associated with the interface are permitted to do and how that should be achieved. For example, the standard or specification may define if the user, or more precisely user device, is provided with a circuit switched bearer or a packet switched communication, or both. Communication protocols and/or parameters which should be used for the connection are also typically defined. For example, the manner in which communication should be implemented between the user device and the elements of the access system is typically based on a predefined communication protocol. One or more gateway nodes may be provided for connecting an access network to other communication networks, for example to an IP (Internet Protocol) and/or other packet switched data networks, thereby enabling use of the resources, for example applications, provided by the data networks.
An access interface may be provided by a fixed line or wireless communication interface. Examples of fixed line access technologies include public switched telephone networks (PSTN), cable networks, local area networks (LAN), digital subscriber line (DSL) networks, asynchronous DSL (ADSL) networks and so on. Communication systems providing wireless access enable at least some degree of mobility for the users thereof. More advanced mobility support can typically be added as an enhanced feature. An example of systems providing wireless access interfaces is a public land mobile network (PLMN) or a cellular mobile system. Other examples of wireless access technologies include various wireless local area networks (WLANs) and satellite based systems.
A communication device may be configured to be capable of accessing a communications system by means of a plurality of different access interfaces. This requires that the communication device is compatible with different access technologies. For example, sophisticated mobile devices are provided with multi-radio capabilities and may therefore access services via a number of access technologies. For example, a mobile device may connect to services provided via the communications system by setting up a PDP context with a third generation (3G) access network, or by setting up a connection through a non-cellular complementary access system, for example a WLAN. According to other examples, a device can be configured to for both wireless access and fixed line access or for access via two different fixed connections.
This means that a user of a communication device is provided with the possibility to choose one of a plurality of access networks for communication with an application provided in the network. Because of the different nature of the access systems substantially different features such as networking protocols and applications may be used by the different access technologies. A result of this is that all access networks may not offer similar level of service and similar features. Thus it is not always possible to use every available access system for a particular network application, or an access system for all available applications. Thus a particular application may not be compatible with all of the available access systems, and therefore a selection of an appropriate access system may be required.
Selecting an access system for the communication media is a blind procedure. Typically, when an application starts communication over the connection, it uses a preconfigured network interface without any additional information that might be needed in providing the application required connectivity. The application may only request the end user to select an appropriate access network or to configure the selected access network in an appropriate manner. A user of a communication device can then decide which network or access method shall be used for each application, and configure the device accordingly, typically via a menu selection.
As the number of available applications and access systems increases, this can lead to an unfavourable user experience as trial and error may have to be used to discover, which access methods support which services. Automation of the access network selection would, however, be desirable to enhance usability of the devices and applications.
Also, as the end user or client is expected to select manually an access network for providing the communication medium for a connection between the end user and the application, the end user is also expected to solve any problems that may occur.
Some of the applications available are local in the sense that they may be associated with a specific access network. For example, downloading of ring tones, some other downloading applications and accessing of an email server may work only when using a cellular data connection via a cellular network of a given operator. This may hinder use of other services and even the mobility of the user. For example, when such services are used a mobile communication device cannot perform handoffs between different access interfaces.
If a wrong access network is selected, or the network is wrongly configured, the data packets may be silently lost in the network without them ever reaching the destination. It may take several minutes for a Transport Control Protocol (TCP) connection to time out in the lack of response from the other end, because a TCP sender cannot know whether packet losses are caused by a transient network problem, by a permanent condition in the network structure or for some other reason.
A similar problem may occur during a handoff of a mobile device. A mobile device does not necessarily know whether a new access network supports the same routing and service characteristics than the old access network, and more particularly, if characteristics and features required by the application are supported. Therefore, selection of a wrong access network may cause the connection to the application to be dropped. This may, however, be realized only after a time out period, possibly only after several minutes.
In accordance with an attempt to solve this problem a communication device may be configured to have a destination network identity (ID) list for each access interface. The list defines appropriate access interfaces for a given service. However, use of destination network IDs is not an application level concept. Instead, the lists have to be configured by the user or provisioned otherwise individually into each communication device. This can be troublesome and preventive of a wide spread use of the destination network IDs.